TalkTalk 500 looks like a front runner for £40 a month. I know their support is shocking but i'm hoping I don't really need to speak to them like when I was last on TT.
Sky only go to 150 by the looks.
BT are a strong alternative to TT, although i'd be going with the 300 package with them I think. 2 year deal though.
Zen, i'm not keen on the 2 year deal.
IDnet, pricey, Aquiss are another alternative but are a little more expensive. AAISP only do 150 and Uno I am strongly considering - due to them offering a 12 month deal. Pulse8 330Mbps looks very good.
Most of your options are going to be 18 month contracts anyway: Aquiss is 12 month, but limited to 150M, which sounds like it rules them out for you.
It's a good time to take out BT right now. You can get 3 months free, no setup charge, and good monthly price. BT's support doesn't have a much better reputation than TT though. Make sure you check all the various links to get the best package price for the speed you want:
Zen may be a longer contract, but at least the price doesn't automatically increase at the end, so it saves hassle and gives you more flexibility should you wish to switch later.
Of the residential providers, BT, Sky and Zen give you IPv6. Zen gives you static IPs. These may or may not be important to you.
IOT isn't going to use much bandwidth, so I'd expect it to be OK.